1. Field of the Invention
The present invention relates to an interior illuminator for an automobile which is provided on the ceiling of the automobile and illuminates the interior of the automobile.
2. Description of the Related Art
A conventional known illuminator for illuminating the interior of an automobile uses a light bulb as a light source. The illuminator of this type is attached to the ceiling of the automobile and illuminates the interior when a switch is manipulated by an occupant or when a door switch is turned on by the opening of a door. However, in the case of using a light bulb as the light source, the light bulb has to be a large one to achieve an adequate light quantity, and therefore, the light bulb disadvantageously protrudes significantly into the interior of the automobile. To avoid this, a plurality of small light bulbs may be used to achieve the same light quantity as the large one. In this case, however, there is a problem that the heat generation, as well as the power consumption, increases, and the illumination light becomes uneven in the illumination range.
Another known illuminator uses a fluorescent lamp as a light source (see Japanese Patent Laid-Open No. 10-129345, for example). The fluorescent lamp consumes less electric power and illuminates more evenly than the light bulb. However, as with the light bulb, there is a problem that the fluorescent lamp has to be large to achieve an adequate quantity of light, although the fluorescent lamp is elongated compared with the light bulb. In addition, the fluorescent lamp requires a relatively large driving circuit to turn the lamp on and, thus, is difficult to downsize, so that there is a problem that the fluorescent lamp protrudes significantly from the ceiling of the automobile. Furthermore, the fluorescent lamp has no directivity of illumination, the light may leak to the driver's seat or be reflected in a window glass. Furthermore, the fluorescent lamp requires a long time to turn on after energization and requires a further time to reach a normal quantity of light after turning on. Therefore, the fluorescent lamp cannot turn on immediately after a door is opened, and a light bulb has to be additionally used to realize illumination associated with opening of the doors, resulting in problems of the increased number of parts and assembling steps, and thus the increased cost, as well as the increased size.
To solve the problems described above, an object of the present invention is to provide an interior illuminator for an automobile that prevents light leakage to the driver's seat and light reflection in a window glass, can illuminate a backseat more evenly with an adequate quantity of light, consumes less electric power, generates less heat, has a small size and can be produced at a reduced cost.